Method and system for ofdm based mimo system with enhanced diversity

ABSTRACT

Certain aspects of a method and system for orthogonal frequency division multiplexing (OFDM) based multi-input multi-output (MIMO) system having enhanced diversity are disclosed. Aspects of one method may include selecting a group of antennas from a plurality of antennas within a radio frequency (RF) system. Data may be communicated via the selected group of antennas. The selected group of antennas may comprise at least one polarized antenna that is orthogonally polarized with respect to adjacent polarized antennas. The plurality of coherently polarized antennas may be placed at a particular distance from each other.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application makes reference to:

-   U.S. application Ser. No. ______ (Attorney Docket No. 17783US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17784US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17785US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17786US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17787US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17788US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17789US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17790US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17791US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17792US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17916US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17917US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17918US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17919US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17920US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17922US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17923US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17924US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17925US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17926US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17927US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17928US01),    filed on even date herewith;-   U.S. application Ser. No. ______ (Attorney Docket No. 17929US01),    filed on even date herewith; and-   U.S. application Ser. No. ______ (Attorney Docket No. 17930US01),    filed on even date herewith.

Each of the above referenced applications is hereby incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communicationsystems. More specifically, certain embodiments of the invention relateto a method and system for an orthogonal frequency division multiplexing(OFDM) based multi-input multi-output (MIMO) system having enhanceddiversity.

BACKGROUND OF THE INVENTION

In most current wireless communication systems, nodes in a network maybe configured to operate based on a single transmit and a single receiveantenna. However, for many current wireless systems, the use of multipletransmit and/or receive antennas may result in an improved overallsystem performance. These multi-antenna configurations, also known assmart antenna techniques, may be utilized to reduce the negative effectsof multipath and/or signal interference may have on signal reception.Existing systems and/or systems which are being currently deployed, forexample, CDMA-based systems, TDMA-based systems, WLAN systems, andOFDM-based systems such as IEEE 802.11 a/g/n, may benefit fromconfigurations based on multiple transmit and/or receive antennas. It isanticipated that smart antenna techniques may be increasingly utilizedboth in connection with the deployment of base station infrastructureand mobile subscriber units in cellular systems to address theincreasing capacity demands being placed on those systems. These demandsarise, in part, from a shift underway from current voice-based servicesto next-generation wireless multimedia services that provide voice,video, and data communication.

The utilization of multiple transmit and/or receive antennas is designedto introduce a diversity gain and array gain and to suppressinterference generated within the signal reception process. Suchdiversity gains improve system performance by increasing receivedsignal-to-noise ratio, by providing more robustness against signalinterference, and/or by permitting greater frequency reuse for highercapacity. Systems that utilize multiple transmit and multiple receiveantenna may be referred to as multiple-input multiple-output (MIMO)systems. One attractive aspect of multi-antenna systems, in particularMIMO systems, is the significant increase in system capacity that may beachieved by utilizing these transmission configurations. For a fixedoverall transmitted power, the capacity offered by a MIMO configurationmay scale with the increased signal-to-noise ratio (SNR).

In order to transfer maximum energy or power between a transmit and areceive antenna, both antennas should have the same spatial orientation,the same polarization sense and the same axial ratio. When the antennasare not aligned or do not have the same polarization, there may be areduction in energy or power transfer between the two antennas. Thisreduction in power transfer may reduce the overall system efficiency andperformance. When the transmit and receive antennas are both linearlypolarized, physical antenna misalignment may result in a polarizationmismatch loss.

Multipath signals may arrive at a mobile handset antenna via thereflection of the direct signal off of nearby objects. If the reflectingobjects are oriented such that they are not aligned with thepolarization of the incident wave, the reflected wave may experience ashift in polarization shift. The resultant or total signal available tothe receiver at either end of the communications link may be a vectorsummation of the direct signal and all of the multipath signals. In manyinstances, there may be a number of signals arriving at the receive sitethat are not aligned with the polarization of the system antenna. As thereceive antenna rotates from vertical to horizontal, it may intercept orreceive energy from these multiple signals.

In polarization diversity systems, a dual linear polarized antenna maybe utilized to receive samples and track the polarization outputproviding the strongest signal level. Each output may provide a totalsignal that may be a combination of all incident signals. This combinedsignal may be a function of the amplitude and phase of each signal aswell as the polarization mismatch of each signal.

Transmit antenna diversity may be utilized to obtain diversity gainagainst Rayleigh fading in wireless systems where the mobile user has alimited number of antennas. Antenna hopping may utilize transmitantennas to obtain diversity gain. With antenna hopping, cyclic orpseudo-random hopping may be used to transform spatial diversity intotime diversity, which may be exploited by, appropriate error correctioncodes and interleaving techniques, but the interleaving requirementsand/or possible bandwidth expansion may incur latency due to the errorcorrection code.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A method and/or system for an orthogonal frequency division multiplexing(OFDM) based multi-input multi-output (MIMO) system, substantially asshown in and/or described in connection with at least one of thefigures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a block diagram illustrating a radio frequency (RF) systemwith a wireless communication host device and an associated radio, inaccordance with an embodiment of the invention.

FIG. 1B is a diagram that illustrates antenna polarization in wirelesscommunication systems, in accordance with an embodiment of theinvention.

FIG. 1C is a block diagram of an exemplary OFDM based multi-inputmulti-output MIMO system, in accordance with an embodiment of theinvention.

FIG. 2 is a block diagram of an exemplary radio frequency (RF) receiver,in accordance with an embodiment of the invention.

FIG. 3A is a diagram that illustrates an exemplary antenna architecturefor multi-antenna orthogonal frequency division (OFD) based systems, inaccordance with an embodiment of the invention.

FIG. 3B is a diagram that illustrates another exemplary antennaarchitecture for multi-antenna orthogonal frequency division (OFD) basedsystems, in accordance with an embodiment of the invention.

FIG. 4 is a block diagram of an exemplary switching mechanism in OFDMbased multi-input multi-output MIMO system, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor an orthogonal frequency division multiplexing (OFDM) basedmulti-input multi-output (MIMO) system having enhanced diversity.Certain aspects of the invention may include selecting a group ofantennas from a plurality of antennas within a radio frequency (RF)system. Data may be communicated via the selected group of antennas. Theselected group of antennas may comprise at least one polarized antennathat is orthogonally polarized with respect to adjacent polarizedantennas. The plurality of polarized antennas may be placed at aparticular distance from each other.

FIG. 1A is a block diagram illustrating a radio frequency (RF) systemwith a wireless communication host device and an associated radio, inaccordance with an embodiment of the invention. Referring to FIG. 1A,there is shown a radio frequency (RF) system 100 that comprises awireless communication host device 10 and an associated RF subsystem 60.

The wireless communication host device 10 may comprise a processingmodule 50, a memory 52, a radio interface 54, an input interface 58 andan output interface 56. The processing module 50 and the memory 52 maybe enabled to execute a plurality of instructions. For example, for acellular telephone host device, the processing module 50 may be enabledto perform the corresponding communication functions in accordance witha particular cellular telephone standard.

The radio interface 54 may be enabled to allow data to be received fromand transmitted to the RF subsystem 60. The radio interface 54 may beenabled to provide the data received from the RF subsystem 60 to theprocessing module 50 for further processing and/or routing to the outputinterface 56. The output interface 56 may be enabled to provideconnectivity to an output device such as a display, monitor, or speakerssuch that the received data may be displayed. The radio interface 54 maybe enabled to provide data from the processing module 50 to the RFsubsystem 60. The processing module 50 may be enabled to receive theoutbound data from an input device such as a keyboard, keypad, ormicrophone via the input interface 58 or generate the data itself. Theprocessing module 50 may be enabled to perform a corresponding hostfunction on the data received via input interface 58 and/or route it toRF subsystem 60 via radio interface 54.

For cellular telephone hosts, RF subsystem 60 may be a built-incomponent. For personal digital assistants hosts, laptop hosts, and/orpersonal computer hosts, the RF subsystem 60 may be built-in or anexternally coupled component. The RF subsystem 60 may comprise a hostinterface 62, a digital receiver processing module 64, ananalog-to-digital converter 66, a filtering/gain module 68, adown-conversion module 70, a low noise amplifier 72, a receiver filtermodule 71, a transmitter/receiver (Tx/Rx) switch module 73, a localoscillation module 74, a memory 75, a digital transmitter processingmodule 76, a digital-to-analog converter 78, a filtering/gain module 80,an up-conversion module 82, a power amplifier 84, a transmitter filtermodule 85, and a plurality of antennas, antenna 1 86 a, antenna 2 86 b,and antenna 3 86 c operatively coupled as shown. The antenna 2 86 b maybe shared by the transmit and receive paths as regulated by the Tx/Rxswitch module 73.

Antenna 1 86 a may be polarized with a zero degree polarization angle,for example. Antenna 2 86 b may be orthogonally polarized with respectto antenna 1 86 a, and may have a 90 degree polarization angle. Antenna3 86 c may be orthogonally polarized with respect to antenna 2 86 b, andmay be coherently polarized with respect to antenna 1 86 a, and may havea zero degree or 180 degree polarization angle. The plurality ofcoherently polarized antennas, antenna 1 86 a, and antenna 3 86 c may beplaced at a particular distance, d apart from each other. The pluralityof antennas, antenna 1 86 a, antenna 2 86 b, and antenna 3 86 c may beconfigured so as to provide isolation in space and/or time. Thepolarized antennas, antenna 1 86 a, antenna 2 86 b, and antenna 3 86 cmay enable reduction of space between the antennas and may provideisolation.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in the memory 75, may be enabled to execute digital receiverfunctions and digital transmitter functions, respectively. The digitalreceiver functions may comprise, but are not limited to, demodulation,constellation demapping, decoding, and/or descrambling. The digitaltransmitter functions may comprise, but are not limited to, scrambling,encoding, constellation mapping, and modulation. The digital receiverand the transmitter processing modules 64 and 76, respectively, may beimplemented using a shared processing device, individual processingdevices, or a plurality of processing devices, for example, amicroprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions.

The memory 75 may be a single memory device or a plurality of memorydevices. For example, the memory 75 may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, and/or any device that stores digitalinformation. When the digital receiver processing module 64 and/or thedigital transmitter processing module 76 implements one or more of itsfunctions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory storing the corresponding operationalinstructions may be embedded with the circuitry comprising the statemachine, analog circuitry, digital circuitry, and/or logic circuitry.The memory 75 may be enabled to store, and digital receiver processingmodule 64 and/or digital transmitter processing module 76 may be enabledto execute, operational instructions corresponding to at least some ofthe functions illustrated herein.

In operation, the RF subsystem 60 may be enabled to receive outbounddata from the wireless communication host device 10 via host interface62. The host interface 62 may be enabled to route outbound data to thedigital transmitter processing module 76. The digital transmitterprocessing module 76 may be enabled to process the outbound data inaccordance with a particular wireless communication standard orprotocol, for example, IEEE 802.11a, IEEE 802.11b, ZigBee, and Bluetoothto produce digital transmission formatted data. The digital transmissionformatted data may be a digital baseband signal or a digital low IFsignal, where the low IF may be in the frequency range of one hundredkilohertz to a few megahertz, for example.

The digital-to-analog converter 78 may be enabled to convert the digitaltransmission formatted data from the digital domain to the analogdomain. The filtering/gain module 80 may be enabled to filter and/oradjusts the gain of the analog baseband signal prior to providing it tothe up-conversion module 82. The up-conversion module 82 may be enabledto directly convert the analog baseband signal, or low IF signal, intoan RF signal based on a transmitter local oscillation 83 provided by thelocal oscillation module 74. The power amplifier 84 may enableamplification of the RF signal to produce an outbound RF signal, whichmay be filtered by the transmitter filter module 85. The antenna 86 bmay be enabled to transmit the outbound RF signal to a targeted devicesuch as a base station, an access point and/or another wirelesscommunication device.

The RF subsystem 60 may be enabled to receive an inbound RF signal viaantenna 86 b, which was transmitted by a base station, an access point,or other wireless communication device. The antenna 86 b may be enabledto communicate the inbound RF signal to the receiver filter module 71via Tx/Rx switch module 73, where Rx filter module 71 bandpass filtersinbound RF signal. The Rx filter module 71 may be enabled to communicatethe filtered RF signal to the low noise amplifier 72, which may amplifythe inbound RF signal to generate an amplified inbound RF signal. Thelow noise amplifier 72 may be enabled to communicate the amplifiedinbound RF signal to the down-conversion module 70, which may directlyconvert the amplified inbound RF signal into an inbound low IF signal orbaseband signal based on a receiver local oscillation 81 provided bylocal oscillation module 74. The down-conversion module 70 may beenabled to communicate the inbound low IF signal or baseband signal tothe filtering/gain module 68. The filtering/gain module 68 may beenabled to filter and/or attenuate the inbound low IF signal or theinbound baseband signal to produce a filtered inbound signal.

The analog-to-digital converter 66 may be enabled to convert thefiltered inbound signal from the analog domain to the digital domain togenerate digital reception formatted data. The digital receiverprocessing module 64 may be enabled to decode, descramble, demap, and/ordemodulate digital reception formatted data to recapture inbound data.The host interface 62 may be enabled to communicate the recapturedinbound data to the wireless communication host device 10 via the radiointerface 54.

The local oscillation module 74 may be enabled to adjust an outputfrequency of a received local oscillation signal. The local oscillationmodule 74 may be enabled to receive a frequency correction input toadjust an output local oscillation signal to generate a frequencycorrected local oscillation signal output.

FIG. 1B is a diagram that illustrates antenna polarization in wirelesscommunication systems, in accordance with an embodiment of theinvention. Referring to FIG. 1B, there is shown a polarized antenna 150.The energy radiated by the polarized antenna 150 may be a transverseelectromagnetic wave that comprises an electric field and a magneticfield. These fields are always orthogonal to one another and orthogonalto the direction of propagation. The electric field E of theelectromagnetic wave may be utilized to describe its polarization. Thetotal electric field of the electromagnetic wave may comprise two linearcomponents, which are orthogonal to one another. Each of thesecomponents may have a different magnitude and phase. At any fixed pointalong the direction of propagation, the total electric field may tracean ellipse as a function of time. For example, at any instant in time,Ex is the component of the electric field in the x-direction and Ey isthe component of the electric field in the y-direction. The totalelectric field E, is the vector sum of Ex and Ey.

The elliptical polarization may comprise two cases, for example,circular polarization and linear polarization. A circularly polarizedelectromagnetic wave may comprise two linearly polarized electric fieldcomponents that are orthogonal, have equal amplitude and may be 90degrees out of phase. In this case, the polarization ellipse traced bythe wave is a circle. Depending upon the direction of rotation of thecircularly polarized wave, the wave may be left hand circularlypolarized or right hand circularly polarized. The phase relationshipbetween the two orthogonal components, +90 degrees or −90 degrees,determines the direction of rotation. A linearly polarizedelectromagnetic wave may comprise a single electric field component andthe polarization ellipse traced by the wave is a straight line.

FIG. 1C is a block diagram of an exemplary OFDM based multi-inputmulti-output MIMO system, in accordance with an embodiment of theinvention. Referring to FIG. 1C, the RF system 170 may comprise adedicated physical channel (DPCH) block 126, a plurality of mixers 128,130 and 132, a plurality of combiners 134 and 136, a first antennaswitch (SW1) 135, a second antenna switch (SW2) 137, a first group oftransmit antennas 138 and 140, a second group of antenna 139 and 141,and an antenna controller 145 on the transmit side. On the receive side,the RF system 170 may comprise a plurality of receive antennas 106_(1 . . . M), a single weight generator (SWG) 110, a plurality of RFblocks 114 _(1 . . . P), a plurality of chip matched filters (CMF) 116_(1 . . . P), and a baseband (BB) processor 126.

The DPCH 126 may be enabled to receive a plurality of input channels,for example, a dedicated physical control channel (DPCCH) and adedicated physical data channel (DPDCH). The DPCH 126 may simultaneouslycontrol the power of DPCCH and DPDCH. The mixer 128 may be enabled tomix the output of DPCH 126 with a spread and/or scrambled signal togenerate a spread complex valued signal that may be input to mixers 130and 132. The mixers 130 and 132 may weight the complex valued inputsignals with weight factors W₁ and W₂, respectively, and may generateoutputs to a plurality of combiners 134 and 136 respectively. Thecombiners 134 and 136 may combine the outputs generated by mixers 130and 132 with common pilot channel 1 (CPICHL) and common pilot channel 2(CPICH2) respectively. The common pilot channels 1 and 2 may have afixed channelization code allocation that may be utilized to measure thephase amplitude signal strength of the channels.

The SW1 135 and the SW2 137 may comprise suitable logic, circuitry,and/or code that may be enabled to select from signals at two outputports, one of which may be coupled to an input port. The SW1 135 and SW2137 may be implemented by utilizing, for example, single pull doublethrow (SPDT) switching devices or by utilizing a multiplexer (MUX), forexample. The selection operation of the SW1 135 and SW2 137 may becontrolled by a control signal such as a transmission control (TX_CTL)signal generated by the antenna controller 145. The SW1 135 may beenabled to switch between the plurality of antennas, 138 and 139alternately in order to transmit communication signals from theplurality of antennas. The SW2 137 may be enabled to switch between theplurality of antennas, 140 and 141 alternately in order to transmitcommunication signals from the plurality of antennas.

The plurality of antennas, 138, 139, 140, and 141 may comprise suitablelogic, circuitry, and/or code that may be enabled to providetransmission of communication signals. In this regard, the plurality ofantennas, 138, 139, 140, and 141 may be utilized for transmission of aplurality of communication protocols. The plurality of antennas, 138,139, 140, and 141 may be configured so as to provide isolation in spaceand/or time. The polarized antennas, 138, 139, 140, and 141 may enablereduction of space between the antennas and may provide isolation. Thefirst group of antennas 138 and 140, or the second group of antennas,139 and 141 may receive the generated outputs from the combiners 134 and136 and may transmit wireless signals based on the position of theantenna switched SW1 135 and SW2 137.

The plurality of receive antennas 106 _(1 . . . M) may each receive atleast a portion of the transmitted signal. The SWG 110 may comprisesuitable logic, circuitry, and/or code that may be enabled to determinea plurality of weights to be applied to each of the input signalsR_(1 . . . M). The SWG 110 may be enabled to modify the phase andamplitude of a portion of the transmitted signals received by theplurality of receive antennas 106 _(1 . . . M) and generate a pluralityof output signals RF_(1 . . . P).

The plurality of RF blocks 114 _(1 . . . P) may comprise suitable logic,circuitry, and/or code that may be enabled to process an RF signal. TheRF blocks 114 _(1 . . . P) may perform, for example, filtering,amplification, and analog-to-digital (A/D) conversion operations. Theplurality of transmit antennas 138 and 140 may transmit the processed RFsignals to a plurality of receive antennas 106 _(1 . . . M). The singleweight generator SWG 110 may comprise suitable logic, circuitry, and/orcode that may be enabled to determine a plurality of weights, which maybe applied to each of the input signals. The single weight generator SWG110 may be enabled to modify the phase and amplitude of at least aportion of the signals received by the plurality of receive antennas 106_(1 . . . M) and generate a plurality of output signals RF_(1 . . . P).The plurality of RF receive blocks 114 _(1 . . . P) may comprisesuitable logic, circuitry and/or code that may be enabled to amplify andconvert the received analog RF signals RF_(1 . . . P) down to baseband.The plurality of RF receive blocks 114 _(1 . . . P) may each comprise ananalog-to-digital (A/D) converter that may be utilized to digitize thereceived analog baseband signal.

The plurality of chip matched filters (CMF) 116 _(1 . . . P) maycomprise suitable logic, circuitry and/or code that may be enabled tofilter the output of the plurality of RF receive blocks 114 _(1 . . . P)so as to produce in-phase (I) and quadrature (Q) components (I, Q). Inthis regard, in an embodiment of the invention, the plurality of chipmatched filters (CMF) 116 _(1 . . . P) may comprise a pair of digitalfilters that are enabled to filter the I and Q components. The outputsof the plurality of chip matched filters (CMF) 116 _(1 . . . P) may betransferred to the BB processor 126.

The BB processor 126 may be enabled to receive a plurality of in-phaseand quadrature components (I, Q) from a plurality of chip matchedfilters (CMF) 116 _(1 . . . P) and generate a plurality of basebandcombined channel estimates ĥ₁ to ĥ_(P). The BB processor 126 may beenabled to generate a plurality of estimates {circumflex over (X)}₁ to{circumflex over (X)}_(P) of the original input spatial multiplexingsub-stream signals or symbols X₁ to X_(P). The BB processor 126 may beenabled to separate the different space-time channels utilizing a BellLabs Layered Space-Time (BLAST) algorithm, for example, by performingsub-stream detection and sub-stream cancellation. The capacity oftransmission may be increased almost linearly by utilizing the BLASTalgorithm.

The plurality of cluster path processors CPP 118 _(1 . . . P) maygenerate a plurality of baseband combined channel estimates ĥ₁ to ĥ_(k)that may correspond to the plurality of receive antennas 106_(1 . . . M). The channel estimator 122 may comprise suitable logic,circuitry, and/or code that may be enabled to process the receivedestimates ĥ₁ to ĥ_(P) from the BB processor 126 and may generate amatrix Ĥ of processed estimated channels.

FIG. 2 is a block diagram of an exemplary radio frequency (RF) receiverantenna architecture for orthogonal frequency division (OFD) basedsystems, in accordance with an embodiment of the invention. Referring toFIG. 2, there is shown a RF receiver 200. The RF receiver 200 maycomprise a plurality of polarized antennas 210 _(1,2, . . . ,M), and 211_(1,2, . . . ,M), a plurality of switches 209 _(1,2, . . . ,M), aplurality of amplifiers 212 _(1,2, . . . ,M), an antenna controller 223,a weight generation block 214, a plurality of filters 220_(1,2, . . . ,N), a local oscillator 222, a plurality of mixers 224_(1,2, . . . ,N), a plurality of analog to digital (A/D) converters 226_(1,2, . . . ,N) and a baseband processor 230.

The plurality of switches SW_(1,2, . . . ,M) 209 _(1,2, . . . ,M) maycomprise suitable logic, circuitry, and/or code that may be enabled toselect from signals at two input ports, one that may be connected to anoutput port. The plurality of switches SW_(1,2, . . . ,M), 209_(1,2, . . . ,M) may be implemented by utilizing, for example, singlepull double throw (SPDT) switching devices, switching transistors, or byutilizing a multiplexer (MUX), for example. The selection operation ofthe plurality of switches SW_(1,2, . . . ,M), 209 _(1,2, . . . ,M) maybe controlled by a control signal such as a receive control (RX_CTL)signal generated by the antenna controller 223. For example, switch 1(SW₁) 209 ₁ may be enabled to switch between the plurality of antennas,210 ₁ and 211 ₁ alternately in order to receive communication signalsfrom the plurality of antennas. Similarly, switch M (SW_(M)) may beenabled to switch between the plurality of antennas, 210 _(M) and 211_(M) alternately in order to receive communication signals from theplurality of antennas.

The plurality of antennas, 210 _(1,2, . . . ,M), and 211_(1,2, . . . ,M) may comprise suitable logic, circuitry, and/or codethat may be enabled to provide transmission and/or reception ofcommunication signals. In this regard, the plurality of antennas, 210_(1,2, . . . ,M), and 211 _(1,2, . . . ,M) may be utilized for receptionof a plurality of communication protocols. The plurality of antennas,210 _(1,2, . . . ,M), and 211 _(1,2, . . . ,M) may be configured so asto provide isolation in space and/or time. The antennas, 210_(1,2, . . . ,M), and 211 _(1,2, . . . ,M) may be polarized to enablereduction of space between the antennas and to provide isolation. Thefirst group 207 of antennas, 210 _(1,2, . . . ,M), or the second group205 of antennas, 211 _(1,2, . . . ,M) may be selected to receive thecommunication signals based on selected group of antennas by theplurality of antenna switches 209 _(1,2, . . . ,M).

In accordance with an embodiment of the invention, a plurality ofantennas that are placed adjacently to at least one polarized antennamay be orthogonally polarized with respect to their adjacent placedpolarized antennas. For example, antenna 1 210 ₁ may be polarized with azero degree polarization angle. Antenna 2 210 ₂ may be orthogonallypolarized with respect to antenna 1 210 ₁, and may have a 90 degreepolarization angle. Antenna 3 210 ₃ may be orthogonally polarized withrespect to antenna 2 210 ₂, and may be coherently polarized with respectto antenna 1 210 ₁, and may have a zero degree or 180 degreepolarization angle. Similarly, antenna M-1 210 _(M-1) may have a zerodegree polarization angle, for example. Antenna M-2 210 _(M-2) andantenna M 210 _(M) may be orthogonally polarized with respect to antennaM-1 210 _(M-1), and may each have a 90 degree polarization angle.

The plurality of coherently polarized antennas, antenna 1 210 ₁, antenna3 210 ₃, and antenna 5 210 ₅ may be placed at a particular distance, d1,apart from each other. The plurality of coherently polarized antennas,antenna 2 210 ₂, antenna 4 210 ₄, and antenna 6 210 ₆ may be placed at aparticular distance, d2, apart from each other. In an embodiment of theinvention, the particular distance, d1, may or may not be equal to theparticular distance, d2.

The amplifiers 212 _(1,2, . . . ,M) may be enabled to amplify the Mreceived input RF signals. The weight generation block 214 may comprisea plurality of amplitude and phase shifters to compensate for the phasedifference between various received input RF signals. Weights may beapplied to each of the input signals A_(1 . . . M) to modify the phaseand amplitude of a portion of the transmitted signals received by theplurality of receive antennas 212 _(1 . . . M) and generate a pluralityof output signals R_(F . . . N). The plurality of filters 220_(1,2, . . . ,N) may be enabled to filter frequency components of the RFsubstreams. The mixers 224 _(1,2, . . . ,N) may be enabled todownconvert the analog RF substreams to baseband. The local oscillator222 may be enabled to provide a signal to the mixers 224_(1,2, . . . ,N), which may be utilized to downconvert the analog RFsubstreams to baseband. The analog to digital (A/D) converters 226_(1,2, . . . ,N) may be enabled to convert the analog basebandsubstreams into their corresponding digital substreams. The basebandprocessor 230 may be enabled to process the digital baseband substreamsand multiplex the plurality of digital signals to generate outputsignals.

In operation, the RF signals may be received by a plurality of Mpolarized antennas 210 _(1,2, . . . ,M) or 211 _(1,2, . . . ,M) at thereceiver 200. Each of the M received signals may be amplified by arespective low noise amplifier 212 _(1,2, . . . ,M). A plurality ofweights may be applied to each of the input signals A_(1 . . . M) tomodify the phase and amplitude of a portion of the transmitted signalsreceived by the plurality of receive antennas 212 _(1 . . . M). Aplurality of output signals RF_(1 . . . N) may be generated, which maybe filtered by a plurality of filters 220 _(1,2, . . . ,N). Theresulting N filtered signals may then be downconverted to basebandutilizing a plurality of N mixers 224 _(1,2, . . . N), each of which maybe provided with a carrier signal that may be generated by a localoscillator 222. The N baseband signals generated by the mixers 224_(1,2, . . . ,N) may then be converted to digital signals by a pluralityof analog to digital (A/D) converters 226 _(1,2, . . . ,N). The Ndigital signals may further be processed by a baseband processor 230 togenerate the output signals.

In one embodiment of the invention, the baseband processor 230 may beoperating in accordance with one or more standards, including but notlimited to, IEEE 802.11, Bluetooth, ZigBee, advanced mobile phoneservices (AMPS), global systems for mobile communications (GSM), codedivision multiple access (CDMA), local multi-point distribution systems(LMDS), Worldwide Interoperability for Microwave Access (WiMAX), fourthgeneration (4G), orthogonal frequency division multiplexing (OFDM) basedsystems, digital video broadcasting handheld (DVB-H),multi-channel-multi-point distribution systems (MMDS), globalpositioning system (GPS), frequency modulation (FM), enhanced data ratesfor GSM evolution (EDGE) and/or variations thereof.

FIG. 3A is a diagram that illustrates an exemplary antenna architecturefor multi-antenna orthogonal frequency division (OFD) based systems, inaccordance with an embodiment of the invention. Referring to FIG. 3A,there is shown a RF system 300 that comprises a plurality of antennas,antenna 1 302, antenna 2 304, antenna 3 306, antenna 4 308, antenna 5310, and antenna 6 312.

The plurality of antennas, antenna 1 302, antenna 2 304, antenna 3 306,antenna 4 308, antenna 5 310, and antenna 6 312 may comprise suitablelogic, circuitry, and/or code that may be enabled to providetransmission and reception of RF communication signals. In this regard,the plurality of antennas, antenna 1 302, antenna 2 304, antenna 3 306,antenna 4 308, antenna 5 310, and antenna 6 312 may be utilized fortransmission and reception of a plurality of communication protocolsincluding but not limited to, IEEE 802.11, Bluetooth, advanced mobilephone services (AMPS), global systems for mobile communications (GSM),code division multiple access (CDMA), local multi-point distributionsystems (LMDS), Worldwide Interoperability for Microwave Access (WiMAX),fourth generation (4G), orthogonal frequency division multiplexing(OFDM) based systems, digital video broadcasting handheld (DVB-H),multi-channel-multi-point distribution systems (MMDS), globalpositioning system (GPS), frequency modulation (FM), enhanced data ratesfor GSM evolution (EDGE) and/or variations thereof.

Antenna 1 302 may be polarized with a zero degree polarization angle,for example. Antenna 2 304 may be orthogonally polarized with respect toantenna 1 302, and may have a 90 degree polarization angle. Antenna 3306 may be orthogonally polarized with respect to antenna 2 304, and maybe coherently polarized with respect to antenna 1 302, and may have azero degree or 180 degree polarization angle. Similarly, antenna 4 308may have a 90 degree polarization angle, antenna 5 310 may have either azero degree or 180 degree polarization angle, and antenna 6 312 may havea 90 degree polarization angle. The plurality of coherently polarizedantennas, antenna 1 302, antenna 3 306, and antenna 5 310 may be placedat a particular distance, d1, apart from each other. The plurality ofcoherently polarized antennas, antenna 2 304, antenna 4 308, and antenna6 312 may be placed at a particular distance, d2, apart from each other.In an embodiment of the invention, the particular distance, d1, may ormay not be equal to the particular distance, d2.

The plurality of antennas, antenna 1 302, antenna 2 304, antenna 3 306,antenna 4 308, antenna 5 310, and antenna 6 312 may be configured so asto provide isolation in space and/or time. The polarized antennas,antenna 1 302, antenna 2 304, antenna 3 306, antenna 4 308, antenna 5310, and antenna 6 312 may enable reduction of space between theantennas and may provide isolation.

FIG. 3B is a diagram that illustrates another exemplary antennaarchitecture for multi-antenna orthogonal frequency division (OFD) basedsystems, in accordance with an embodiment of the invention. Referring toFIG. 3B, there is shown a RF system 300 that comprises a plurality ofantennas that may be arranged in a matrix 350. Each cell within thematrix may comprise one polarized antenna.

Antenna 1 in the first cell 362 may be polarized with a zero degreepolarization angle, for example. Antenna 2 in the adjacent cell 364 maybe orthogonally polarized with respect to antenna 1 in the first cell360, and may have a 90 degree polarization angle. Antenna 3 in the thirdcell 366 may be orthogonally polarized with respect to antenna 1 in cell362, and may be coherently polarized with respect to antenna 2 in cell364, and may have a 90 degree polarization angle. Similarly, antenna 4in cell 368 may be coherently polarized with respect to antenna 1 incell 362, and may be orthogonally polarized with respect to antenna 2 incell 364, and antenna 3 in cell 366, and may have either a zero degreeor 180 degree polarization angle. Antenna 5 in cell 370 may becoherently polarized with respect to antenna 4 in cell 368, and may beorthogonally polarized with respect to antenna 3 in cell 366, and mayhave either a zero degree or 180 degree polarization angle. Antenna 6 incell 372 may be orthogonally polarized with respect to antenna 5 in cell370, and may have a 90 degree polarization angle.

The plurality of coherently polarized antennas, antenna 1 in cell 362,antenna 4 in cell 368, and antenna 5 in cell 370 may be placed at aparticular distance, d1, apart from each other. The plurality ofcoherently polarized antennas, antenna 2 in cell 364, antenna 3 in cell366, may be placed at a particular distance, d2, apart from each other.The plurality of coherently polarized antennas, antenna 3 in cell 366and antenna 6 in cell 372 may be placed at a particular distance, d2,apart from each other. In an embodiment of the invention, the particulardistance, d1, may or may not be equal to the particular distance, d2.

FIG. 4 is a block diagram of an exemplary switching mechanism in OFDMbased multi-input multi-output MIMO system, in accordance with anembodiment of the invention. Referring to FIG. 4, there is shown aportion of a RF system 400 that comprises a plurality of antennaswitches, switch 1 410, switch 2 412, switch 3 414, and switch 4 416, afirst group of antennas 420, and a second group of antennas 430. Thefirst group of antennas 420 may comprise a plurality of antennas,antenna 1 422, antenna 2 424, antenna 3 426, and antenna 4 428. Thesecond group of antennas 430 may comprise a plurality of antennas,antenna 5 432, antenna 6 434, antenna 7 436, and antenna 8 438.

The plurality of antenna switches, switch 1 410, switch 2 412, switch 3414, and switch 4 416 may comprise suitable logic, circuitry, and/orcode that may be enabled to select from signals at two input ports, oneof which may be coupled to an output port. The plurality of switchesswitch 1 410, switch 2 412, switch 3 414, and switch 4 416 may beimplemented by utilizing, for example, single pull double throw (SPDT)switching devices, switching transistors, or by utilizing a multiplexer(MUX), for example. The selection operation of the plurality of switchesswitch 1 410, switch 2 412, switch 3 414, and switch 4 416 may becontrolled by a control signal such as a transmission control (TX_CTL)signal or receive control (RX_CTL) signal generated by the antennacontroller 405.

For example, switch 1 410 may be enabled to switch between the pluralityof antennas, antenna 1 422 and antenna 5 432 alternately in order totransmit and/or receive communication signals to/from the plurality ofantennas. Switch 2 412 may be enabled to switch between the plurality ofantennas, antenna 2 424 and antenna 6 434 alternately in order totransmit and/or receive communication signals to/from the plurality ofantennas. Switch 3 414 may be enabled to switch between the plurality ofantennas, antenna 3 426 and antenna 7 436 alternately in order totransmit and/or receive communication signals to/from the plurality ofantennas. Switch 4 416 may be enabled to switch between the plurality ofantennas, antenna 4 428 and antenna 8 438 alternately in order totransmit and/or receive communication signals to/from the plurality ofantennas.

The plurality of antennas, antenna 1 422, antenna 2 424, antenna 3 426,antenna 4 428, antenna 5 432, antenna 6 434, antenna 7 436, and antenna8 438 may comprise suitable logic, circuitry, and/or code that may beenabled to provide transmission and/or reception of communicationsignals. In this regard, the plurality of antennas, antenna 1 422,antenna 2 424, antenna 3 426, antenna 4 428, antenna 5 432, antenna 6434, antenna 7 436, and antenna 8 438 may be utilized for transmissionand/or reception of a plurality of communication protocols. Theplurality of antennas, antenna 1 422, antenna 2 424, antenna 3 426,antenna 4 428, antenna 5 432, antenna 6 434, antenna 7 436, and antenna8 438 may be configured so as to provide isolation in space and/or time.The plurality of antennas, antenna 1 422, antenna 2 424, antenna 3 426,antenna 4 428, antenna 5 432, antenna 6 434, antenna 7 436, and antenna8 438 may be polarized to enable reduction of space between the antennasand to provide isolation. The first group of antennas 420, or the secondgroup 430 may be selected to transmit and/or receive communicationsignals based on the selected group of antennas by the plurality ofantenna switches, switch 1 410, switch 2 412, switch 3 414, and switch 4416.

In accordance with an embodiment of the invention, a plurality ofantennas that are placed adjacently to at least one polarized antennamay be orthogonally polarized with respect to their adjacent placedpolarized antennas. For example, antenna 1 422 may be polarized with azero degree polarization angle. Antenna 2 424 may be orthogonallypolarized with respect to antenna 1 210 ₁, and may have a 90 degreepolarization angle. Antenna 3 426 may be orthogonally polarized withrespect to antenna 2 424, and may be coherently polarized with respectto antenna 1 422, and may have a zero degree or 180 degree polarizationangle. Antenna 4 428 may be orthogonally polarized with respect toantenna 3 426, and may have a 90 degree polarization angle. Similarly,antenna 5 432 may be polarized with a 90 degree polarization angle, forexample. Antenna 6 434 may be orthogonally polarized with respect toantenna 5 432, and may have a zero degree polarization angle. Antenna 6436 may be orthogonally polarized with respect to antenna 2 434, and maybe coherently polarized with respect to antenna 1 432, and may have a 90degree polarization angle. Antenna 4 438 may be orthogonally polarizedwith respect to antenna 3 436, and may be coherently polarized withrespect to antenna 3 436 and may have a zero degree or 180 degreepolarization angle.

The plurality of coherently polarized antennas, antenna 1 422, andantenna 3 426 may be placed at a particular distance, d1, apart fromeach other. The plurality of coherently polarized antennas, antenna 2424, antenna 4 428 may be placed at a particular distance, d2, apartfrom each other. Similarly, the plurality of coherently polarizedantennas, antenna 5 432, and antenna 7 436 may be placed at a particulardistance, d1, apart from each other. The plurality of coherentlypolarized antennas, antenna 6 434, antenna 8 438 may be placed at aparticular distance, d2, apart from each other. In an embodiment of theinvention, the particular distance, d1, may or may not be equal to theparticular distance, d2. Notwithstanding, the RF system 400 may comprisea plurality of groups of antennas, and each switch may be enabled toswitch between a plurality of antennas.

In accordance with an embodiment of the invention, a method and systemfor orthogonal frequency division multiplexing (OFDM) based multi-inputmulti-output (MIMO) system having enhanced diversity may comprise aplurality of antenna switches, switch 1 410, switch 2 412, switch 3 414,and switch 4 416 within a radio frequency (RF) system 400 comprising aplurality of antennas, for example, antenna 1 422, antenna 2 424,antenna 3 426, antenna 4 428, antenna 5 432, antenna 6 434, antenna 7436, and antenna 8 438 that may enable selection of at least one groupof antennas, for example, a first group of antennas 420, or a secondgroup of antennas 430.

The selected group of antennas, for example, the first group of antennas420, may comprise at least one polarized antenna, for example, antenna 1422, that may be orthogonally polarized with adjacent polarizedantennas, for example, antenna 2 424. The polarized antenna, forexample, antenna 1 422 may be placed at a particular distance, d1 fromat least one other polarized antenna, for example, antenna 3 426 that iscoherently polarized with respect to the polarized antenna, antenna 1422. The adjacent polarized antenna, antenna 2 424 may be placed at aparticular distance, d2 from at least one other polarized antenna,antenna 4 428, that is coherently polarized with respect to the adjacentpolarized antenna, antenna 2 424.

At least one polarized antenna, antenna 3 426 that is orthogonallypolarized with respect to adjacent polarized antennas, antenna 2 424 andantenna 4 428 may be enabled to transmit and/or receive data. Theplurality of antenna switches, switch 1 410, switch 2 412, switch 3 414,and switch 4 416 may be enabled to switch between a plurality ofselected groups of antennas, for example, a first group of antennas 420or a second group of antennas 430. The plurality of antenna switches,switch 1 410, switch 2 412, switch 3 414, and switch 4 416 may beenabled to select at least one antenna from the selected group ofantennas for communicating data. For example, switch 1 410 may beenabled to switch between the plurality of antennas, antenna 1 422 andantenna 5 432 alternately in order to transmit and/or receivecommunication signals to/from the plurality of antennas. Switch 2 412may be enabled to switch between the plurality of antennas, antenna 2424 and antenna 6 434 alternately in order to transmit and/or receivecommunication signals to/from the plurality of antennas.

Another embodiment of the invention may provide a machine-readablestorage, having stored thereon, a computer program having at least onecode section executable by a machine, thereby causing the machine toperform the steps as described above for orthogonal frequency divisionmultiplexing (OFDM) based multi-input multi-output (MIMO) system havingenhanced diversity. For example, any one or more of the components inthe wireless communication host device 10 and/or the RF subsystem 60 maybe controlled via code such as software and/or firmware. In this regard,in an exemplary embodiment of the invention, any one or more of thedigital receiver processing module 64, ADC 66, filtering/gain module 68,down-conversion module 70, LNA 72 and Rx filter module 71 may beprogrammably controlled by code comprising software and/or firmware. Inanother exemplary embodiment of the invention, any one or more of thedigital transmitter processing module 76, DAC 78, filtering/gain module80, up-conversion module 82, PA 84, and Tx filter module 86, may beprogrammably controlled by code comprising software and/or firmware.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for processing signals in a communication network, themethod comprising: in a radio frequency (RF) system comprising aplurality of antennas, selecting at least one group of antennas fromsaid plurality of antennas; and communicating data via said selected atleast one group of antennas comprising at least one polarized antennathat is orthogonally polarized with respect to adjacent polarizedantennas.
 2. The method according to claim 1, comprising placing said atleast one polarized antenna at a particular distance from at least oneother polarized antenna that is coherently polarized with respect tosaid at least one polarized antenna.
 3. The method according to claim 1,comprising placing each of said adjacent polarized antennas at aparticular distance from at least one other polarized antenna that iscoherently polarized with respect to each of said adjacent polarizedantennas.
 4. The method according to claim 1, comprising transmittingsaid data via said at least one polarized antenna that is orthogonallypolarized with respect to said adjacent polarized antennas.
 5. Themethod according to claim 1, comprising receiving said data via said atleast one polarized antenna that is orthogonally polarized with respectto said adjacent polarized antennas.
 6. The method according to claim 1,comprising switching between a plurality of said selected at least onegroup of antennas.
 7. The method according to claim 1, comprisingselecting at least one antenna from said selected at least one group ofantennas for communicating said data.
 8. A machine-readable storagehaving stored thereon, a computer program having at least one codesection for processing signals in a communication network, the at leastone code section being executable by a machine for causing the machineto perform steps comprising: in a radio frequency (RF) system comprisinga plurality of antennas, selecting at least one group of antennas fromsaid plurality of antennas; and communicating data via said selected atleast one group of antennas comprising at least one polarized antennathat is orthogonally polarized with respect to adjacent polarizedantennas.
 9. The machine-readable storage according to claim 8, whereinsaid at least one code section comprises code for placing said at leastone polarized antenna at a particular distance from at least one otherpolarized antenna that is coherently polarized with respect to said atleast one polarized antenna.
 10. The machine-readable storage accordingto claim 8, wherein said at least one code section comprises code forplacing each of said adjacent polarized antennas at a particulardistance from at least one other polarized antenna that is coherentlypolarized with respect to each of said adjacent polarized antennas. 11.The machine-readable storage according to claim 8, wherein said at leastone code section comprises code for transmitting said data via said atleast one polarized antenna that is orthogonally polarized with respectto said adjacent polarized antennas.
 12. The machine-readable storageaccording to claim 8, wherein said at least one code section comprisescode for receiving said data via said at least one polarized antennathat is orthogonally polarized with respect to said adjacent polarizedantennas.
 13. The machine-readable storage according to claim 8, whereinsaid at least one code section comprises code for switching between aplurality of said selected at least one group of antennas.
 14. Themachine-readable storage according to claim 8, wherein said at least onecode section comprises code for selecting at least one antenna from saidselected at least one group of antennas for communicating said data. 15.A system for processing signals in a communication network, the systemcomprising: at least one circuit within a radio frequency (RF) systemthat enables selection of at least one group of antennas from aplurality of antennas; and said at least one circuit enablescommunication of data via said selected at least one group of antennas,wherein said selected at least one group of antennas comprises at leastone polarized antenna that is orthogonally polarized with respect toadjacent polarized antennas.
 16. The system according to claim 15,wherein said at least one polarized antenna is placed at a particulardistance from at least one other polarized antenna that is coherentlypolarized with respect to said at least one polarized antenna.
 17. Thesystem according to claim 15, wherein each of said adjacent polarizedantennas is placed at a particular distance from at least one otherpolarized antenna that is coherently polarized with respect to each ofsaid adjacent polarized antennas.
 18. The system according to claim 15,wherein said at least one circuit enables transmission of said data viasaid at least one polarized antenna that is orthogonally polarized withrespect to said adjacent polarized antennas.
 19. The system according toclaim 15, wherein said at least one circuit enables receiving of saiddata via said at least one polarized antenna that is orthogonallypolarized with respect to said adjacent polarized antennas.
 20. Thesystem according to claim 15, wherein said at least one circuit enablesswitching between a plurality of said selected at least one group ofantennas.
 21. The system according to claim 15, wherein said at leastone circuit enables selection of at least one antenna from said selectedat least one group of antennas for communicating said data.